JP2912286B2 - Fuel-saving lubricating oil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel-saving lubricating oil for an internal combustion engine, and more particularly, it is suitable as a lubricating oil for a gasoline engine. The present invention relates to a lubricating oil having excellent shear stability.

[0002]

2. Description of the Related Art From the viewpoint of saving energy and suppressing emission of carbon dioxide, which contributes to global warming, it is required to improve the fuel efficiency of automobiles. In order to improve the fuel efficiency of automobiles, the weight of automobiles has been reduced, and the amount of lubricating oil mounted on automobiles tends to decrease. For this reason, a lubricating oil with higher performance is required. Lubricating oil for the engine originally works to keep the inside of the engine clean, to reduce friction loss in sliding parts such as bearings, pistons / cylinders, and valve trains, and to prevent wear. Used to move to. However, in the movement as described above, it is expected that lubricating oils are further provided with fuel-saving performance.

[0003]

In order to reduce friction loss due to engine oil, it is effective to reduce the viscosity of engine oil, and various studies have been made. However, simply lowering the viscosity of the lubricating oil increases the wear on the sliding parts, increases the evaporation loss of the lubricating oil, deteriorates the exhaust gas properties, and reduces the amount of lubricating oil. The deterioration speed of the oil may increase. Furthermore, the viscosity of the lubricating oil in a high temperature range decreases, and the risk of seizure wear increases in sliding parts such as a valve train and a bearing.

In order to suppress an increase in the evaporation loss of the lubricating oil, there is a method of using a synthetic lubricating oil having a narrow boiling point range. However, the use of a synthetic lubricating oil significantly increases the cost as compared with the case where a mineral base oil is used. Also,
In order to prevent the seizure wear described above due to a decrease in the viscosity of the lubricating oil, there is a method of adding an additive such as an extreme pressure agent, an antiwear agent or a friction modifier. However, extreme pressure agents,
Even if additives such as an antiwear agent or a friction modifier are added, it is not possible to prevent evaporation loss of the lubricating oil.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil using a low-cost mineral base oil, which has a great effect of reducing friction loss by oil for an internal combustion engine, is excellent in energy saving, and has a low evaporation amount while having a low viscosity. Another object of the present invention is to provide a fuel-saving lubricating oil for an internal combustion engine, which has a small decrease in the viscosity of the lubricating oil in a high temperature range and has excellent shear stability.

[0006]

The fuel-saving lubricating oil for an internal combustion engine according to the present invention has a kinematic viscosity at 100 ° C. of 3 to 3.
It is characterized in that an organic molybdenum compound is blended in a mineral oil base oil having a viscosity index of 135 or more with an organic molybdenum compound of 50 to 1000 ppm (weight) in terms of molybdenum amount. In a preferred embodiment of the present invention, a mineral base oil obtained by hydroisomerizing a wax is used.

[0007]

The present inventors have conducted intensive studies on the physical properties of lubricating base oils for internal combustion engines, the effects of additives, and the like. As a result, by combining the effects of specific additives with the properties of specific base oils, The present inventors have found that the present invention is remarkably exhibited far beyond the expectation, and completed the present invention.

It is important that the mineral base oil used in the present invention has a low viscosity and a high viscosity index. Specifically, a mineral base oil having a kinematic viscosity at 100 ° C. of 3 to 5 cSt and a viscosity index of 135 or more must be used.

When the kinematic viscosity of the mineral base oil is less than 3 cSt, evaporation loss is large even if the viscosity index is 135 or more.
On the other hand, if the kinematic viscosity exceeds 5 cSt, the expected energy saving performance cannot be obtained. Mineral base oil has a viscosity index of 135
If it is less than, the evaporation loss increases as compared with a mineral base oil having the same kinematic viscosity, and the temperature dependence of the viscosity increases, so that the viscosity decreases significantly at a high temperature of about 150 ° C. or higher, Lubricity deteriorates and the risk of seizure wear increases.

[0010] It is further interesting that molybdenum dithiophosphate (MoD
TP), molybdenum dithiocarbamate (MoDTC)
It has been found that the addition of such an organic molybdenum compound has the effect of synergistically improving the lubricity, and that the energy saving performance of the lubricating oil is significantly improved.

Even if the kinematic viscosity of the mineral base oil is 3 to 5 cSt, if its viscosity index is less than 135, the addition of an organic molybdenum compound improves the energy saving performance to some extent. There is no noticeable synergistic effect as in the invention. In addition, the evaporation property and shear stability of the lubricating oil deteriorate. Viscosity index of mineral base oil is 14
When it is 0 or more, the energy saving performance of the lubricating oil is further improved.

Furthermore, the pour point of the mineral base oil is preferably -10 ° C. or lower, and the boiling point is preferably 330 ° C. or higher. If the pour point exceeds −10 ° C., the low-temperature viscosity increases, which hinders lubricity at low temperatures, and tends to make it difficult to obtain good low-temperature startability when mounted on an automobile. In addition, when a fraction having a boiling point lower than 330 ° C. enters, the flash point tends to decrease, and the evaporation loss tends to increase even if the viscosity index is 135 or more. More preferably, a mineral base oil having a pour point of -15 ° C or lower and a boiling point of 340 ° C or higher is used.

The mineral base oil described above may be any mineral oil satisfying the above-mentioned properties, and various mineral oils can be used without any particular limitation.

Usually, in order to obtain a mineral oil-based lubricating base oil, first, a paraffin-based crude oil or an intermediate-based crude oil is subjected to atmospheric distillation,
Alternatively, the distillation residue is further distilled under reduced pressure to obtain a distillate oil. Then, known purification processes such as hydrorefining, dewaxing (solvent dewaxing, hydrodewaxing), solvent extraction (furfural, etc.), alkali distillation, sulfuric acid washing, clay treatment, etc. may be used alone or several processes as appropriate. And then processing the distillate oil to obtain a mineral base oil. However, even if crude oil is carefully selected, the above-mentioned refining process is processed in a complicated combination, and the quality of intermediate products is strictly controlled,
It is practically almost impossible to obtain a mineral base oil having a kinematic viscosity at 00 ° C. of 3 to 5 cSt and a viscosity index of 135 or more and usable in the present invention.

Further, slack wax produced as a by-product in the dewaxing step in producing a mineral oil-based lubricating oil or wax obtained by Fischer-Tropsch synthesis (hereinafter referred to as F / T wax) is hydroisomerized, By dewaxing after distillation or fractionation after dewaxing, a low-viscosity, high-viscosity mineral oil-based base oil having the above properties can be obtained relatively easily and in high yield. When added, lubricating properties are synergistically improved.

For example, a kinematic viscosity of 4 to 10 c at a boiling point range of 300 to 700 ° C., carbon number of 20 to 70, and 100 ° C.
St slack wax is added to the alumina carrier by Ni-Mo.
Alternatively, in the presence of a catalyst supporting Ni-W, a hydrogen partial pressure of 5
0-260Kg / cm ² , temperature 300-410 ° C, L
Hydroisomerization under the reaction conditions of HSV 0.1-2.0 Hr ^-1 gives an isomerized oil. Then, a mixed solvent such as methyl ethyl ketone (MEK) / toluene is added to
De-wax the isomerized oil using a 5-fold volume at a temperature of -10 to -25 ° C and optionally distill before or after the dewaxing step to give an initial boiling point of 330 ° C, Viscosity 3-5 cSt
(100 ° C.) and a mineral oil having a viscosity index of 135 or more can be obtained in a high yield of about 40 to 60%.

By treating the F / T wax in the same manner as the slack wax described above, the lubricating oil of the present invention can
It can be preferably used. To obtain the F / T wax, a hydrocarbon-containing substance (for example, natural gas or coal) is used.
Is converted to a mixture of carbon monoxide and hydrogen by a known method, and a hydrocarbon is synthesized from the mixture of carbon monoxide and hydrogen using an iron, ruthenium or cobalt catalyst (Fischer-Tropsch synthesis). The heavy fraction of the synthesized hydrocarbon is the F / T wax referred to herein.
Unlike wax obtained by refining crude oil, F / T wax is a solid paraffin wax that does not contain sulfur, nitrogen, metal impurities, etc., has a high linear paraffin content, and is usually solid.

As the mineral base oil of the lubricating oil in the present invention, (A) a mineral oil obtained by a usual lubricating oil production method, and (B) a slack wax as long as the viscosity and viscosity index are within the above ranges. Mineral oil obtained by hydroisomerization and mineral oil obtained by hydroisomerizing (C) F / T wax can be used. Among them, (B) and (C) are particularly preferable,
(B) Mineral oil obtained by hydroisomerizing slack wax is more preferable. Naturally, even if the mineral oil has a low viscosity index, it is mixed with the above-mentioned hydroisomerized oil having a high viscosity index, and if the mixed mineral oil is adjusted to the above-mentioned viscosity and viscosity index ranges, the mixed mineral oil is used as the main oil. It can be used in the invention and can enjoy the effects of the invention. In addition, a synthetic oil such as polyalphaolefin, alkylbenzene, polyalkylene glycol, ester or the like can be appropriately mixed with such a mineral oil base oil as long as the effects of the present invention are not impaired.

The organic molybdenum compound used in the present invention acts synergistically with the above-mentioned mineral base oil having a low viscosity and a high viscosity index, and can exhibit excellent energy saving performance and practical performance. ,It was revealed.

For example, when an organic molybdenum compound is added to base oils having different viscosity indices and equivalent viscosities, the effect of reducing friction in a mineral oil base oil having a low viscosity index is more significant.
The effect of reducing friction in a mineral base oil having a high viscosity index is far greater.

Examples of the organic molybdenum compound include molybdenum dithiophosphate (MoDTP), molybdenum dithiocarbamate (MoDTC), and molybdenum amine complex. Among them, MoDTP, MoDT
C is even more preferred.

The organic molybdenum compound may be added and blended with the finished lubricating oil (composition) in an amount of 50 to 1000 ppm (by weight) in terms of molybdenum amount.
If the amount is less than 50 ppm, the effect of the present invention is not remarkable. On the other hand, even if the organic molybdenum compound is added in excess of 1000 ppm, the effect does not increase as much as the added amount increases. It is even more preferable to add 200 to 500 ppm.

The lubricating oil of the present invention can be easily prepared by using the above-mentioned mineral base oil and the organic molybdenum compound and further adding other additives described below by a known method as appropriate. The viscosity classification of lubricating oil is SAE viscosity classification 0W-20,
It is preferable to use 0W-30, 5W-20 or 5W-30 grade. The lubricating oil of the present invention is CEC L-40
-Evaporation test by the method specified in T-87 (Noac
In k), those having a property of evaporating amount of 15% or less are preferable, and those having a property of 13% or less are more preferable. Such a lubricating oil has a low viscosity but a small amount of evaporation, is excellent in energy saving performance and practical performance, and maintains these high performances.

In the lubricating oil of the present invention, if necessary, various additives which are added to and blended with general lubricating oils for internal combustion engines can be added. Examples of such additives include antioxidants [zinc alkyldithiophosphates having a linear or branched alkyl group (ZnDTP), bisphenol, diphenylamine, etc.], viscosity index improvers [polymethacrylate (PMA), olefin copolymers] Etc.], metal detergents [sulfonates, finates, salicylates, phosphonates, etc. of various metals such as Ca, Mg, Ba, Na, etc.], ashless dispersants (alkenyl succinimide, etc.), other pour point depressants, prevention Rust agents and the like can be exemplified.
These additives can be added at an appropriate ratio according to the properties of the base oil, the use, and other conditions. Each of these additives may be individually added to the mineral base oil,
These additives are blended in an appropriate ratio in advance,
It may be added to the mineral base oil in the form of a so-called package.

[0025]

The present invention will be described more specifically with reference to the following examples. (Production Method and Properties of Mineral Base Oil as Raw Material) As a base material of lubricating oil, a mineral base oil produced as follows was used. Table 1 shows the properties of each mineral base oil.

VHVI1: A slack wax having a boiling point of 400 to 550 ° C. is mixed with a hydrogen partial pressure of about 80 kg / cm ² and a temperature of about 390 ° in the presence of a Ni—Mo supported alumina catalyst.
C, hydroisomerized under the reaction conditions of LHSV 0.5 Hr ^-1 . The obtained isomerized oil was distilled, and a fraction obtained by distilling a fraction of 350 ° C. or less was dewaxed at −20 ° C. using a mixed solvent of MEK / toluene to obtain VHVI1.

VHVI2: Light mineral base oil obtained by distilling VHVI1 under reduced pressure, which is a distillate from the initial distillation to 50% by volume. VHVI3: A heavy mineral oil-based material that is the remaining 50% residue after distilling off VHVI2, a light mineral oil, when VHVI1 is distilled under reduced pressure.

SRO1: a mineral base oil obtained by extracting a fraction having a boiling point of 350 to 500 ° C. (converted to normal pressure) of Arabian light crude oil into furfural solvent, hydrotreating, and dewaxing MEK / toluene solvent. SRO2: boiling point of Arabian light crude oil (normal pressure conversion) 2
Mineral base oil obtained by extracting a fraction at 50 to 450 ° C with furfural solvent, hydrorefining, and dewaxing MEK / toluene solvent.

HCO: A fraction having a boiling point of 250 to 650 ° C. (converted to normal pressure) of Arabian light crude oil is hydrocracked at a conversion of 60%, and a boiling point of 270 ° C. or less is removed by normal pressure distillation. To obtain residual oil. The residual oil was distilled under reduced pressure to obtain a fraction having a boiling point (converted to normal pressure) of 300 to 500 ° C, and this fraction was subjected to furfural solvent purification, hydrogenation purification, and solvent dewaxing treatment to obtain HCO.

[0030]

[Table 1]

(Production of Lubricating Oil) The lubricating oils of Examples 1 to 7 and Comparative Examples 1 to 11 were prepared using the above-mentioned mineral base oils as main raw materials. First, the above-mentioned respective mineral base oils were used alone or in a mixture at a ratio shown in the upper part of Table 2 and Table 3 (by volume ratio) to produce mineral base oils of Examples and Comparative Examples. The viscosity index, kinematic viscosity (100 ° C.) (cSt), amount of evaporation (Noack), pour point (° C.), and initial boiling point (° C.) of the mineral base oils of Examples and Comparative Examples were measured. Are shown in the lower part of Tables 2 and 3, and the measurement method is shown below.

Viscosity index: JIS K2283 Kinematic viscosity (100 ° C.) (cSt): JIS K2283 Evaporation amount (Noack) (% by weight): CEC L-40-
T-87 Pour point (° C): JIS K2269 Initial boiling point: ASTM D2887

[0033]

[Table 2]

[0034]

[Table 3]

Each of the additives (wt%) shown in Tables 4 and 5 was added to the mineral base oil of each example.
As an additive, molybdenum dithiophosphate (Mo)
DTP), molybdenum dithiocarbamate (MoDT)
C), an amine type friction modifier, a SG package and a viscosity index improver (VII) of a polymethacrylate / olefin copolymer mixture were used. SG package is Ca
It is a mixture of sulfonate, Ca finate, ZnDTP, succinimide derivative and rust inhibitor. The content (blending amount) of the organic molybdenum compound in 100 parts by weight of the finished lubricating oil is shown in the lower part of Table 4 and Table 5 in terms of ppm by weight in terms of molybdenum amount.

[0036]

[Table 4]

[0037]

[Table 5]

The kinematic viscosities, HTHS viscosities, and CCS viscosities of the lubricating oils thus obtained were measured. Further, the performance of the lubricating oil was evaluated based on the amount of evaporation (Noack), shear stability, fuel efficiency improvement rate and friction coefficient. The physical property values and evaluation test results of the lubricating oil of each example are shown in Table 6 for Examples 1-7, and in Table 7 for Comparative Examples 1-11.

The measurements and evaluation tests of the physical properties of the lubricating oils of the respective examples were performed according to the following methods. Kinematic viscosity (100 ° C) (cSt): JIS K2283 HTHS viscosity (cP): ASTM D4683 CCS viscosity (-25 ° C) (cP): JIS K221
5 Evaporation amount (Noack) (% by weight): CEC L-40-
T-87 Shear stability (cSt): ASTM STP 509A
A Part B test was performed, and after 10 hours, lubricating oil was sampled and the kinematic viscosity after degassing was measured (L38 bearing wear test).

The fuel efficiency improvement rate was tested under the following test conditions, and evaluated as follows. Test conditions: A 2000 cc inline 4-cylinder gasoline engine was used, the engine speed was 2000 rpm, the dynamo torque was 8 kgfm, the oil temperature was 80 ° C, and the water temperature was 70 ° C. Fuel consumption was measured.

Evaluation: kinematic viscosity 10.3 cSt, total acid value 1.6 mg KOH / g, total base value 5.01 mg KOH / g
g of SAE30 grade lubricating oil was tested under the same test conditions as above, the fuel consumption was measured, and this measured value was used as a reference. The difference between the measured value of the fuel consumption in each case and the reference was divided by the reference, and the fuel efficiency improvement rate (%) was shown as a percentage.

Further, the coefficient of friction under boundary lubrication is 3
The measurement was performed under the following test conditions using a pin-on-disk tester. Test conditions Material (pin, disk) FC30 Load 2500N Rotation speed 700rpm Oil temperature 80 ℃

[0043]

[Table 6]

[0044]

[Table 7]

From the test results shown in Table 2 and Table 7, the following can be seen for the lubricating oils of the examples and the comparative examples. Example 1
The SAE 5W-30 grade lubricating oil of No. 4 has improved fuel economy by 4.5% or more, has excellent shear stability, and has little evaporation compared to the reference SAE 30 grade lubricating oil composition in the fuel economy test. . Among Examples 1-4, Examples 1 and 4 are those in which the viscosity index of the mineral base oil is 14
0 or more, and the initial boiling point is 330 ° C. or more. The lubricating oils of Examples 1 and 4 are particularly excellent in terms of improvement in fuel efficiency, shear stability, and low evaporation.

The lubricating oil of Example 5 was SAE 5W-20
And showed good performance as in Example 1-4. The lubricating oils of Examples 6 and 7 have a kinematic viscosity of 3 to
SAE 5W using 4cSt mineral base oil
-30, 5W-20. Since the amount of evaporation of the mineral base oil is selected to be 18% by weight, which is larger than that of Example 1-5, the amount of evaporation of the lubricating oil increases, but the fuel saving performance is further improved. In addition, all the lubricating oils of Examples 1 to 7 satisfy the performance of API SH class.

On the other hand, the lubricating oil of Comparative Example 1-3 used a mineral base oil having a viscosity index of 135 or more and a kinematic viscosity of 3-5 cSt, but did not add an organic molybdenum compound. Therefore, the fuel efficiency improvement rate is only 2.5% or less, and the friction coefficient exceeds 0.11. The mineral oil base oil having a viscosity index of 143 and a kinematic viscosity of 4.5 cSt is used in the lubricating oil of Comparative Example 4, but the amount of the organic molybdenum compound added is 40 ppm in terms of molybdenum. For this reason, the fuel efficiency improvement rate is only 3.0%, and the friction coefficient is high.

The lubricating oil of Comparative Example 5 was V mineral oil base oil.
Although HVI1 is used and an amine type friction modifier is used in place of the organic molybdenum compound, the same effect as the lubricating oil of the present invention using the organic molybdenum compound can be obtained in terms of fuel efficiency improvement rate and friction coefficient. Not.

In the lubricating oils of Comparative Examples 6 to 8, the kinematic viscosity and the viscosity index of the mineral base oil are out of the range of the present invention. These are S
AE 5W-30 grade lubricating oil, but poor in shear stability (L38 bearing wear test: viscosity after 10 hours as described above) and does not satisfy the SH class standard value of 9.3 to 12.5 .

The lubricating oils of Comparative Examples 9 and 10 have a mineral oil base oil having a viscosity index of 100 or less. The lubricating oil of Comparative Example 11 was
The kinematic viscosity of the mineral base oil exceeds 5 cSt. Even in these lubricating oils, satisfactory fuel economy performance or the like has not been obtained even when an organic molybdenum compound is added.

[0051]

As described above, the fuel-saving lubricating oil for an internal combustion engine according to the present invention has a large effect of reducing friction loss and is excellent in energy saving in a lubricating oil using a low-cost mineral base oil. It has a low viscosity but a small amount of evaporation, a small decrease in the viscosity of the lubricating oil in a high temperature range, and excellent shear stability. Therefore, it is extremely useful especially as a lubricating oil for automobile engines.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10N 20:02 30:06 30:08 40:25 (72) Inventor Kazumitsu Fujiwara 3-17-35 Niisonanami, Toda City, Saitama Prefecture No. Japan Energy Co., Ltd. (56) References JP-A-3-106995 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10M 101/02 C10M 139/00 C10N 10: 12 C10N 20:02 C10N 30:06 C10N 30:08 C10N 40:25

Claims (2)

(57) [Claims] A kinematic viscosity at 100 ° C. of 3 to 5 cS.
t, a mineral oil-based base oil having a viscosity index of 135 or more,
The amount of the organic molybdenum compound is 50
A fuel-saving lubricating oil for an internal combustion engine, wherein the lubricating oil is blended in an amount of from 1000 ppm (by weight). 2. The fuel-saving lubricating oil for an internal combustion engine according to claim 1, wherein the mineral oil base oil is a mineral oil base oil obtained by hydroisomerizing a wax.